1. Field of the Invention
The present invention relates generally to apparatus for controlling the environment of an enclosed space. More particularly, the present invention relates to apparatus for controlling and monitoring the cleanliness and humidity of a workspace for manipulating sensitive materials and articles.
2. Description of Related Art
Industrial processes such as fabrication, assembly, cleaning and packaging have increasingly required greater and more precise control over the environments in which they are conducted. Many laboratory functions as well achieve more satisfactory results when ambient conditions can be closely specified, enhancing reproducibility of experimentation along with such other advantages as freedom from contamination.
Environmental chambers in which the enclosed space is, for example, dehumidified, are well known to the manufacturing and scientific communities. Such chambers may take the form of a free standing upright structure called a "dry box" or "glove box", wherein sensitive materials or articles can be manipulated within a volume sealed off from the atmosphere. Conventional dry boxes, however, are extremely dirty, since particles generated therein are not removed as they form.
Another widely utilized workspace environment control is the so-called "clean room", a part of a building in which airborne contamination is controlled to a far higher degree than in conventionally air-conditioned spaces. Clean rooms are traditionally large enclosures set apart from the rest of the building by floor-to-ceiling partitions. The quality of a clean room is expressed by a class number, which number represents the maximum number of particles 0.5 micron in length or larger per cubic foot of air space. The number of such particles present in an ordinary clean room, hence the class number thereof, is on the order of 100,000. By way of contrast, outside unfiltered air may contain such particles in excess of 600,000,000 per cubic foot. Clearly, the smaller the class number, the cleaner the room; a class number of 10,000 is not uncommon. Even a conventional clean room must be tightly fitted with non-porous, easy to clean surfaces having low particle shedding properties and should have floors with a minimum practical number of joints. The internal pressure of a clean room is maintained above that of surrounding areas to insure outward leakage. An exceptional clean room of Class 100 or even Class 10, which may be required for certain manipulations of sensitive articles, for example, jet spray cleaning thereof, is rare, since setting up such a room is difficult and maintaining it extremely expensive.
Conventional jet spray cleaning operations have consumed large quantities of chlorofluorocarbons (CFC's), compounds whose use is increasingly discouraged by the Federal Environmental Protection Agency. A desirable improvement over old technology would allow the use of manual spray guns and a clean dry box, significantly reducing CFC consumption and waste.
Accordingly it is an object of this invention to provide an environmental control apparatus to ensure that articles and sensitive materials may be manipulated under any desired conditions of humidity and cleanliness.
Another object of this invention is to provide control of airborne contamination in a workspace environment to such an extent that such space has a class number on the order of 10 or smaller, at much less cost of installation and maintenance than that of previously available clean rooms.
A still further object is to provide a combination of workspace conditions and operational equipment that will result in a substantial reduction in the use of environmentally disfavored chemical compounds.